if'n

Etymology 2
. The spelling ef'n is attested since at least 1909. Perhaps a compound of and  (a variant, attested since Middle English, of ; compare  and ); if an is attested since at least the 1700s. Alternatively, perhaps a compound of if and, generalized from conjunctional uses of , , and so on, or of if and as in ,  (which goes back to ), etc. Compare. Lastly, as with the etymology above, it may be a contraction of if (and) when.

Conjunction

 * 1)  If.